Tax & NI

[itbemay]

Just had 2 letters separately one saying I’ve paid too little tax and owe £800 and one saying I have overpaid NI and to fill out a form to claim back. I work 35h pw in one job and 6h pw in another, both employed. How do I find out how this has happened and who would be responsible for the underpayment and overpayment! Would it be my employers? Thx in advance

You can look at all your payslips. You are responsible for an underpayment or overpayment as it is your taxes. Your employer just deducts them from your wages based on information you provide when you start the job and information from HMRC.

The letters will say on them for which tax year they apply, it can date back some way or it may just be 2017/18 (6th April 2017 to 5th April 2018).

Given you have one letter saying you owe money and one saying you can claim back money, I would be inclined to speak to someone at HMRC and have them check. Before doing so I would look at all the payslips for the relevant tax year (if you still have them) to see if you can see where you may have been on the same tax code in both jobs, or something else relating to tax code being incorrect.

Usually you would have your full personal tax allowance, represented by your tax code, in the job in which you earn the most money. Your other job would then run at basic rate tax. If you are a higher rate tax payer then having the second job at basic rate I don't think pays enough income tax.

Thankyou @nannynick